Overload-indicator.



C. F. GILLIATT.

OVERLOAD INDICATOR.

APPLICATION 11.50 JAN. 11. 1909.

1,1 79,624. Patented Apr. 18, 1916.

2 SHEETS-SHEET I.

8 fi a 85 UNITED STATES CHARLES E. GILLIATT, 0F LYNN,

MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGN- A CORPORATION OF PENNSYLVANIA.

ovnnLoAn-INnIcATon.

Specification of Letters Patent.

Patented Apr. 18, 1916.

Application filed January 11, 1909. SerialNo. 471,585.

T 0 all whom it may concern:

Be it known that I, CHARLES F. GILLIATT, a citizen of the United States, residing at Lynn, county of Essex, and State of Massachusetts, have invented an Improvement 1n Overload-Indicators, of which the following description, in connection with the accompanying drawing, is a specification, like letters on the drawing representing like parts.

In electric lighting plants where electricity is furnished to individual consumers I at a cost based upon the average or maxitive,

by an instrument of this type will open mum number of lights used at any given time by any individual consumer, 1t 1s mportant to have some means of indicating when any one patron is using more lamps than his contract calls for. Various devices have been devised for giving such indication by repeatedly opening and closing the circuit thus causing the lamps on the circuit to go out and be lighted again in rapid succession, and many of these devices involve a switch for opening the main circuit, a switch-operating magnet for operating the switch, which magnet is in a normally open shunt circuit and is, therefore, normally inoperaand an auxiliary magnet in the main circuit which becomes energized when the current in the main circuit exceeds a predetermined amount, and which when energized closes the shunt circuit, thereby causing the switch-operating magnet to be energized and the main switch to be opened. Many devices of thi's'character which have been previously devised are so arranged that if they are used with a circuit having a heavy current, the opening and closing of the contacts in the main circuit has a destructive effect upon the instrument.

My inventionrelates to an instrument of the above-mentioned type, and one of the objects of the invention is to provide an of this class which can successinstrument fully operate under a heavy current without injury to the instrument.

Another object is to provide means whered an close the main circuit successively comparatively slowly; and still another object is to provide an improved switch, all as will be more fully hereinafter described and then pointed out in the claims.

My improvements are capable of use either witha three-wire system of distributing current, or with a two-wire system. I have in the drawing, however, shown a switch adapted for use in connection with a threewlre system. I 1

In the drawings, Figure 1 is a section on substantially the line an el r, Fig. 2; Fig. 2

is a section on substantially the line y-y, Flg. 1'; Fig. 3 is a diagram view showing the method of wiring the instrument; Fig.

fl is a top plan view of the casing for the instrument; Fig.5 is a section on the line a-a, F g. 2; Fig. 6 is a section on the line b-b, F g. 2; Fig. 7 is a section on the line 0-0, Flg. 1; Fig. 8 is a top plan View of the auxiliary'switch arm; Fig. 9 is an enlarged section on the line d-d, Fig. 1.

As stated above, the herein-described embodiment of the invention is one adapted for use with the three-wire system, and 3 and 4 designate the outside mains of the system; 5 designates the return or neutral main, 6 the translating devices, and 7 the dynamo or generator. Where the device is employed in connection with such a three-wire "system, I propose to provide for opening a "switch in each of the outside mains when more than a predetermined amount of current is being slate, and these parts are preferably inclosed in a case or box 9 which isadapted to contam oil so that the contacts are made and broken within the body of oil; The construction ofthe particularcase or box here- 1n shown will be more fully hereinafter described.

The switch herein illustrated for opening and closlng the mains comprises two switch blades 10, one for each of the mains 3 and 4, and two contacts 11. Each switch blade 10 is pivoted at 13 to an arm or bracket 12 which is secured to the plate or slab 8. Each arm 12 is shown as being formed with an ear or lug 14 which lies against and is screwed to the plate 8 by means of a screw 15. Each fixed contact 11 is resiliently mounted, it being shown herein as carried which is free and the other end of which is fastened to a flange 19 of a bracket 18 that is also secured to the plate or slab 8. It will be noted that the fixed contacts 11 are situated in a plane at an angle to the plane in which the switch blades 10 move.

The ends 17 of the switch blades which engage the contacts 11 are twisted so as to stand in parallelism with the contacts 11, as seen in Figs. 2, 7 and 9, so that when the switch is closed, the portions 17 of the switch blades lie flatly against the contacts 11. The advantage of this construction is that when each switch blade swings downwardly to close the switch, the end 17 thereof strikes the contact 11 with a sort of glancing blow and a good contact is always insured.

Each spring 16 holds its contact 11in such a position that the contact is engaged by the switch blade 10 before the latter reaches the full downward limit of its movement, and as a consequence, there is a rubbing action between the switch blade and contact while the switch is being completely closed, and at the same time the spring 16 is placed under some tension. In this way, a good contact is made and maintained. When the switch is completely closed, the end of each switch blade rests on the shelf 19 which acts to limit the downward movement of the switch blade. 10 are connected together so that they move in unison, and they are operated by a magnet 20 herein referred to as the main switchoperating magnet. I have herein shown the switch blades 10 as connected by a cross bar 21 of insulating material. This cross bar has connected thereto an arm or projection 22 provided with an aperture 23. The magnet 20 is in the form of a solenoid, and the core 24 thereof is split at its lower end, as at 25, to receive the projection 22, said lower end of the core carrying a pin 26 which passes through the opening 23, see Figs. 2, 6 and 7. When the magnet 20 is energized the core 24 is sucked thereinto and the upward movement of the core swings the switch blades 10 out of engagement with the contacts 11, thus opening the two mains 3 and 4. The aperture 23 is considerablylarger than the pin 26, as best seen in Fig. 6. The purpose of this "is partly so as to permit the core 24 to have a certain amount of movement before it begins to operate the switch so that at the time it does operate the switch,

the core will have acquired suflicient momen-' tum to cause a quick opening movement of the switch, and partly to permit the switch blades to swing in the arc of a circle while the core moves in a straight line. The 'core is shown as having applied thereto a weight;

27 which assists to swing the switch blades downwardly into closed position, as shown in Fig. 2.

The magnet 20 is in the shunt circuit The switch blades iary. magnet 32, and said magnet is con- I nected by a wire 33 to the binding post 34 to which the main 4is also connected. The other main 3 comes into the instrument at the binding post 35 and from said binding post a. wire 38 leads to a second auxiliary magnet 39, said magnet being connected by a wire 40 to the bracket12 supporting the other switch blade 10. The corresponding contact 11 is connected by a wire 41 with the binding post 37 to which the main 3 is connected. When the switch is closed, both mains 3 and 4 are unbrokenv and the current in the two mains will pass through the two magnets 32 and 39 respectively. These magnets are so designed that they will have no effect so long as the current is under the predetermined amount, but if the current exceeds the predetermined amount they are energized sufliciently to set in operation mechanism to close the shunt circuit through the main magnet 20, thus energizing the latter. When the magnet 20 is energized, the core 24 thereof is drawn upwardly thereby opening the contacts in the two mains 3 and 4 and disconnecting the translating devices from the generator.

The armature for the auxiliary magnets 32, 39 is designated by 50. It is carried by an arm 51 forming part of an auxiliary switch and which is supported by a spiral spring 57. The arm 51 normally rests against a stop 58 which holds it in the position shown in Fig. 2. When the magnets 32, 39 are energized, however, the armature 50 is drawn downwardly, t us carrying the end of the arm 51 against the contact 59 which is in the shunt circuit that includes the coils of the magnet 20. This shunt circuit comprises a wire 60 connected to the wire 41, which in turn is connected to the main 3, the coils of the magnet 20, the wire 61 which leads to the bracket 62 that supports the coiled spring 57, said spring 57 and arm 51, contact 59, and wire 63 that leads to the binding post 36, said binding post being connected to the neutral or return 5.

From the above it will be seen that when the current in the main circuit becomes excessive and the magnets 32, 39 become energized, the shunt circuit will be closed through the main magnet 20, thus energizing the latter and opening the contacts in the mains 3 and 4. When the circuit is thus opened, the magnets 32, 39 become dener- 'zed and the auxiliary switch comprising v t e arm 51 will be opened by the action of Accordingly rents of'difi'erent volume.

said magnets with a stop 65 of insulating material against which the armature .50-

rests when the auxiliary switch is closed. The core of the magnets 32, 39 may be sus tained in any suitable way. I have herein shown said core at 67 and the upper end thereof extends through a ring 68 to which it is pinned by a pin 69. The ring 68 inturn rests on the plate 70 on the top of the magnet and preferably said ring will be provided withone vor two pins 71 to enter openings formed in the plate. The amount of current in the coils of the magnets 32, 39 necessary to attract the armature 50 depends upon the resistance of the spring 57. I have herein provided means for adjusting the tension of this spring thereby making the instrument capable of responding to cur- As herein shown one end of the spring 57 is rigidly secured to a sleeve 73 which is loosely mounted on a stud 74 supported at one end in the plate or slab 8, and at the other end in the bracket 62. This sleeve 73 has rigid therewith a.

worm gear 75which meshes with a worm 76 fast on a shaft 77. The shaft 77 is journaled in bearings 78 carried by or rigid withthe bracket 62. Said shaft 77 is provided with a thumb-piece 79 by which it may be turned. It. will be seen that by turning the shaft 79 in one direction or, the

other, the gear 75 and the sleeves 73 will.

be rotated, thereby placing the spring 57 under greater or less tension, that depending on the direction in which the sleeve is turned.

- It will be seen from the above that all the operativeparts of the device are supported by the slab or plate 8. This slab or plate is preferably placed in a box or casing- 9 which is adapted to contain oil, so that the contacts in both the main and the shunt circuits will be made and broken in oil.

'This has the advantage that a heavy current can be carried by the circuits without danger of injuring the contacts when they are made and opened as would occur with- .out the presence of oil. The slab 8 is shown as resting on two blocks 80 which in turn rest on the bottom of thecasing 9, said blo'cks being provided with notches through which the lower edge of the slab or plate is received. The upper end of the slab or plate is secured to the back of the casing 9 by screws 81. The upper end of the casing 9 is open and is normally closed by a cover 82. This cover is provided with side wings 83 which overlie the sides of the casing 9 and which are provided at their rear edges withhooks 84 that are adapted to enter apertures 85 formed in extensions on the back of the casing 9. The front of the cover is provided with an opening 86 through which a staple 87 on the front of the casing extends. When the cover is in place, as shown in 'Figs.'2 and 4, and seal 88'is applied to the staple, it will beimpossible' to remove the cover without first breaking the seal, for the cover can only be removed by swinging the front of it forwardly sufficiently to per mit the hooks 4 to be disengaged from the apertures 85. The openings through the top of the casing through which the wires extend are formed partially in the removable cover and partially in the casing. As herein shown, the casing has rigid therewith a plate 90 of insulating material which extends across the top thereof and which is provided with the notches 91. The cover 82 is similarly provided with a plate 93 of, insulating material which has notches in its edge that aline with the notches 91, said alined notches forming the openings through which the wires extend. This construction has the advantage-that when the cover 82 is removed, the wires are perfectly accessible and the instrument may be wired up or disconnected without the necessity of drawing the wires through apertures in the top or side of the casing.

My invention also comprehends a device for retarding the opening and closing moves ment of the auxiliary switch. The purpose ofthis is to provide a construction in which the contacts in the main circuit are opened and closed'comparatively slowly so that the lights will go out and come on again at intervals of a few seconds. In the present embodiment of my invention I accomplish this end by providing the arm 51 of the auxiliary switch with a vane having sufficient surface so that the-oil will retard its movement therethroughQit bein understood that the box or casing 9 is su ciently full of oil so that the oil covers the auxiliary switch arm 51. This vane is herein shown as in the form of a disk 99 which s secured to the arm 51, although the vane might have any other shape without departing from the invention.

While I have shown been one embodi- 'ment of. myinvention I do not wish to be limited thereto as various changes injthe details of construction might be made without affecting the scope of the claims.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent is 1. In a device of the class described, the combination with a switch comprising a fixed and a movable contact, of a spiral spring sustaining the movable contact, a stud, a sleeve mounted on the stud to which one end of the spiral spring is fastened, and means to adjust the sleeve about the stud thereby to vary the tension of the spring.

2. In a device of the class described, the combination with a switch comprising fixed and movable contacts, of a spiral spring sustaining the movable contact, a rotatable member to which the inner end of the spring is fastened, said member having gear teeth thereon, and a worm-gear meshing with said gear teeth and by which the member may be turned to vary the tension of the spring. 7

3. In an overload indicator, the combination with a support of insulating material, of a bracket secured thereto and presenting a laterally-extending flange, a contact resiliently carried by the bracket, an arm secured to the support and extending outwardly and downwardly therefrom, a switch blade pivoted to the lower end of said arm and adapted to engage the contact by gravity, and a magnet for elevating the switch blade, the flange and said bracket limiting intense I the downward movement of the switch blade.

4. In an overload indicator, the combinato the support above the brackets and ex- I tending outwardly and downwardly from the support, a switch blade pivoted to the lower end of each arm and arranged to move in a vertical plane, the end "of each switch blade being situated at an angle to its movement to engage the contact, and a magnet for raising said switch blades, said flanges of the brackets limiting the closing movement of the switch blades.

5. In a device of the class described, the combination with a box or casing, of two notched supports secured to the bottom thereof, a plate or slab of insulating material having its lower edges sustained in said notches, means to'secure the upper portion of said slab or plate to the back of the cas ing, and a switch carried by said plate.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses. I

' CHARLES F. GILLIATT. Witnesses:

Louis C. SMITH, THOMAS J. DRUMMOND. 

